ptr_pack.hpp

#pragma once
 
#include <array>
#include <tuple>
 
namespace lmp::tensor::detail::cpu::internal {
 
template <typename U, typename V>
struct TransformFunctor {
  U operator()(void* p, std::size_t i) const {
    return static_cast<U>(static_cast<V*>(p)[i]);
  }
};
 
 
template <class OutT, class... SrcTs>
class PtrPack {
 public:
  static constexpr std::size_t kN = sizeof...(SrcTs);
 
  ::std::array<void*, kN + 1> data;
  ::std::tuple<TransformFunctor<OutT, OutT>, TransformFunctor<OutT, SrcTs>...>
      fns;
 
  constexpr explicit PtrPack(OutT* out, SrcTs*... in)
      : data{static_cast<void*>(out), static_cast<void*>(in)...},
        fns{TransformFunctor<OutT, OutT>{},
            TransformFunctor<OutT, SrcTs>{}...} {}
 
  void set_Out(std::size_t idx, OutT value) {
    static_cast<OutT*>(data[0])[idx] = value;
  }
};
 
}  // namespace lmp::tensor::detail::cpu::internal